In conventional packaging of a back-type opto-electronic device, solder balls are typically planted over electrodes of a bare die so that the solder balls are welded onto a packaging print circuit board (PCB). In order to improve the reliability, padding material may be filled between the bare die and the packaging PCB. However, this structure is prone to cracking when temperature changes, due to a significant difference of thermal expansion coefficient between material of the conventional packaging PCB and material (Si) of the bare die.
In addition, when packaging is done, the packaged back-type opto-electronic device will be welded onto a corresponding circuit board in a second welding process. If regular soldering is used, in the second welding process, the solder balls planted over the bare die will be melted for a second time. If low temperature soldering is used instead, higher requirements must be applied to the welding process and the solder itself, and failure to meet these requirements will easily cause trouble in welding.
Novel packaging techniques are desired in order to at least partially address the above issues.